Cancel 'zoom' when user hit 'Escape'

Author: lambdalisue

autoload/fern/mapping/drawer.vim

@@ -26,6 +26,9 @@ function! s:map_zoom(helper) abort
   if alpha <= 0 || alpha > 10
     let current = float2nr(ceil(str2float(winwidth(0)) / &columns * 10))
     let alpha = s:input_alpha(printf('Width ratio [%d -> 1-10]: ', current))
+    if alpha is# v:null
+      return
+    endif
   endif
   let alpha = str2float(alpha)
   let width = &columns * (alpha / 10)
@@ -43,7 +46,10 @@ endfunction
 function! s:input_alpha(prompt) abort
   while v:true
     let result = input(a:prompt)
-    if result =~# '^\%(10\|[1-9]\)$'
+    if result ==# ''
+      redraw | echo ''
+      return v:null
+    elseif result =~# '^\%(10\|[1-9]\)$'
       redraw | echo ''
       return result
     endif